Always be ready for a profound change to cause a short-term step backward with your game. It's a bit of a headache, but if you understand the long-term gains you're working toward (sounds like you do), then it's usually easier to keep on crunching through the rough spots without too much frustration. GOOD to hear that you're already seeing new things happen with your serve - keep on rockin'!!!
As for pronation, don't worry about it. Unless you're elbowing yourself in the stomach when you try to hit a serve, your arm is probably moving just fine. Stay loose and maintain a comfortable tempo in your motion to keep it reliable. The bigger muscles in your legs and core will really make it "go".
One ripple that comes with your grip change could be the need to alter your swing path and toss location a little bit. If you're a righty, you're probably finding it easier to swing through the ball when your toss is slightly more to the right than when you used the eastern forehand grip to serve. Definitely experiment with this.
You'll probably find lots of sidespin when your toss is further off to the right, but a little more heat with that toss shading a little more straight out in front of you. As that continental grip gets more comfortable, you'll be able to do different things to the ball with slight variations in your contact point, racquet angle, and swing path.
Bonus: you can now also use a full motion, even when delivering a second serve. Say goodbye to that paddy-cake second serve because you need decent racquet speed to generate that spin that's starting to crank up. With some more practice, you should hopefully start using the same complete motion for both your first and second serves. That will give you both enough velocity and enough spin, depending on the type of serve you want to hit.